Why is the 17 faster than the 15 ?

Discussion in 'MacBook Pro' started by jetjaguar, Feb 25, 2011.

  1. jetjaguar macrumors 68030


    Apr 6, 2009
    On the article on the front page there is a chart of the performance of the new mbps and it says that the top of the line 17 and base 17 are faster than the high end 15? how is that possible?
  2. orfeas0 macrumors 6502a

    Aug 21, 2010
    Athens, Greece
    no clue, wondering that too. i mean it's the same specs, and the 17" needs more power for the screen too!
  3. benpatient macrumors 68000

    Nov 4, 2003
    there's a lot of trickery involved with the i7 clock speeds and core/thread enabling/disabling that could cause one machine to do something different in a different situation.

    Maybe it was cooler in the room when the 17" was run? Maybe the 15 has a smaller fan that keeps the turbo boost from reaching the same sustained ghz?

    who knows. It's interesting, though.
  4. orfeas0 macrumors 6502a

    Aug 21, 2010
    Athens, Greece
    good point, i guess the 17" fans are better which means real turbo boost!
  5. derbothaus macrumors 601


    Jul 17, 2010
    Trickery? I call it BS. Apple outlets and other partner sites have always ranked the 17" higher. Media seems to fudge numbers to make a better case for the price. Only thing usually faster is maybe the GPU. Same chip but as noted earlier maybe they don't underclock it in the 17". Turbo multiplier bins are most likely the same as Intel usually doesn't "custom" make chips for Apple and Apple rarely gets into such low level tinkering. So again, BS.
  6. RKpro macrumors 6502

    Oct 27, 2008
    I don't know.
    But I suspect, it may have to do with with the 17's larger surface area and interior volume, so it would be slightly better at conducting away the heat. Better heat management means the core i7/i5s can overclock themselves (with turbo boost) more of the time.
  7. Consultant macrumors G5


    Jun 27, 2007
    17" usually has more room, layout might be slightly more optimized.

    17" often runs at slightly higher voltage, etc.
  8. arctic macrumors 6502a


    Jun 18, 2008
    I think this is the best explanation. Perhaps Apple saw the heat problems of the 15" and underclocked it. Coincidentally, StefSSU mentioned the same thing a few minutes ago. It's definitely the turbo boost technology and its heat sensors.
  9. kobyh15 macrumors 6502a

    Jan 29, 2011
    Not an expert here, but I think the 17" just has more physical room in its chassis to allow for better cooling. The processor is then able to turbo boost higher and turbo boost longer without throttling down because of excess heat. That's the best explanation I have.
  10. frogger2020 macrumors regular

    Sep 10, 2006
    It could be that the test scores vary from run to run and the one that was chosen happened to show the 17 as faster than the 15. If the test was run a large number of times, the scores would probably show to be statistically similar.
  11. VTMac macrumors 6502

    Jun 9, 2008
    It's heat dissipation. The 17 dissipates more hart than the 15 in benchmarks that translates to the CPU staying in elevated states longer before reaching it's thermal limits. Hence slightly higher results.
  12. rmitchell248 macrumors 6502

    Mar 30, 2010
    Liebsthal, Germany
    anyone have an article to the link in question?
  13. parseckadet macrumors 6502a


    Dec 13, 2010
    Denver, CO
    To say Apple underclocked the 15" is a misrepresentation of what's going on. Apple didn't underclock anything. If they had they wouldn't be able advertise it at that base clock speed, since it would fall below it. The CPU overclocks itself for as long as it can until it reaches a certain temperature, the it backs off. What others are saying here is that the 15" reaches that target temperature sooner, so it starts stepping back down to the base clock speed sooner. I suspect that if you took the systems out of the case, and provided them with the exact same cooling, that they would behave exactly the same.
  14. adnoh macrumors 6502a


    Nov 14, 2010
    the ipad is not the only thing "truly magical"
  15. arctic macrumors 6502a


    Jun 18, 2008

    So basically, for those planning to upgrade their 15" processors from 2.2GHz to 2.3GHz, they're better off buying a stock 17" 2.2GHz for almost the same cost without the BTO hassle. The stock 17" beats the pants out of an upgraded 15" due to heat dissipation. And you have a cooler machine as well.
  16. AdamRock macrumors 6502a


    Aug 30, 2010
  17. TheHoff macrumors 6502

    Oct 22, 2008
    Except for two things:

    - people usually buy 15 or 17 based on size not relative performance

    - 17" runs at 1900 x 1200 which will be more intensive to run at the native res. than either of the 15"s so you will get lower frame rates
  18. Reminisquare macrumors newbie

    Feb 25, 2011
    Because of the ventilation

    Size of 17 inch chasis makes it more effective in flow of the heat.

    which will increase the maximum performance of the same cpu.

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